I'm currently starting up development of our next commercial game and am looking to use something like this in C# in MonoGame... you raise some valid questions that I hope to see some answers to. Currently not sure if I should implement an interpreter for this for MonoGame or just code a dialogue system myself if 90% of the work is reading the JSON this thing outputs (half of which are editor-only).
It's interesting though. Why even have editor-only values in a production exported JSON? Can't these be saved in some binary save file for the software that you can load in?
I'm also curious to know if adding custom nodes is an option. Is that what the Execute node is for? I guess it could be. Would be nice to have a small editor for a custom node, adding your own controls that would add the same way in the JSON...